Method of making piston rings



March 28, 1939. v. F. ZAHODIAKIN 2,152,123

METHOD OF MAKING PISTON RINGS Filed March 13, 1936 11v VENTOR hw /W A TTORNEYJ Patented Mar. 28, 1 939" UNITED STATES 2.15am v Mn'rnon or MAKING ris'ron RINGS Victor F. Zahodiakin, Na mi, N. Y. Application March is, 1936. Serial No. 68,748

' 3 Claims.

This invention relates to piston rings and the method of manufacturing piston rings, particularly piston rings of the type disclosed in the patent granted to Victor F. Zahodiakin No.

5 1,957,927on'May 8, 1934. The ring disclosed in the mentioned patent is formed from a strip of metal to provide a series of radially disposed passageways opening at the inner and outer periphery of the ring. In connection with the method herein concerned, reference may also be made to the pending application of Victor F. Zahodiakin filed April 10, 1934, Serial No. 719,- 885, in which application, the ring isformed by means of series of dies; It is an object of this invention to provide an improved piston ring and method of forming the same, particularly a ring in which the corrugations forming the oil passageways havetsharp n corners, the invention including for this purpose an improved die action and preferably a special metal strip stock from which the ringsare formed.v

. rings wherein the strip of metal from which 35 the ring is formedmay be oi! low carbon'content,

' the method bringing about the production of a piston ring having the requisite hardness and toughness for the intended use, this result being achieved by the die action on the metal.

40 It has also been found that diflerent'grades of steel must be used as the speed of production .0! the machine varies. v This is particularly true in connection with the present die arrangement in view or the fact that a series or dies are em- 45 ployed, and it is necessary that .these dies have working clearances therebetween for permitting expansion of, the .parts and for lubricating-purposes. If a steel of low carbon content is used; and the machine is operated at high speed, some 50 of the metal will be forced into the clearances between the dies during swaging, creating fins at] PATENT OFFICE low carbon content is delivered to the machine when'itis operating at low speed, and a steel of high carbon content is delivered to the machine when it is operating at high speed.=

Other objects and certain advantages will be 5 more fully apparent irom the drawingjin which:

Figures 1 to 11 inclusive are similar tragmentary views of the piston ring formingmachine vided through a transversely disposed die guide 20' The strip, of metal passes between sets of dies. These dies are operated and timed by any appropriate mechanism such as cams and levers.

For the purpose of identifying the dies throughout the views they have been marked by the numerals I to 9 inclusive. The upper, set consists 4 of dies l to 4 inclusive, and the lower-set 5 to 9 inclusive. As will be apparent from an inspection or the views, the respective dies slide upon 30 each other. In order that they may slide in. an eflicient manner, it is necessary that working clearances be provided, which clearances receive the lubricating oil and permit expansion of the dies and associated parts. A' series of views have been disclosedin order that the multiplicity of die actions may be fully realized, and for the purposev of illustrating the formation of the corrugations and the swaging action for producing square or sharp comers.

edge coinciding with the edge of die a.

In the next view, Figure 2, 'upper dieilhas moved down into engagement with the strip whereby the end or the strip is clamped between dies I and 8. Also dies I, 2, and 3 have moved down very slightly and die 6 has moved the same amount upwardly. Die 3 is then in the proper position for coaction with die I. i

and die 1 has formed one side of a corrugation moving die 9, which is a pilotdie, will be described later since die 9 functions after the strip has progressed further.

In Figure 4, die 2 has moved down completing the corrugation around die I by coaction with dies 6 and I. The corrugation referred to is identified at 20. In Figure 5, die 5 has moved upwardly for the purpose of forming a. portion 2! of the next corrugation.

In Figure 6, dies 2 and I have been retracted a slight amount. Dies I, 5, and 8 remain stationary for the purpose of holding the formed strip. rigidly in position so that during the swaging action, which is to ensue, there is no chance for the strip to become displaced. The vertical walls 22 of the corrugations cannot be'displaced since they are contained betweenthe dies 5, 2, l, and 4. These walls 22, during the swaging action, are confined so rigidly between the dies as to preclude any change in their original dimension or form. The dies may then be referred to as forming a die box within which the swagingcan take place.

The spaces or chambers provided by retraction of dies 2 and 1 are of sufficient size or will contain an amount of metal equal to that which will be swaged into the corners as dies 3 and 6 move against the metal as shown in Figure 7. Dies 3 and 5 have sharp corners and after they force the metal of the crowns of the corrugation toward dies 1 and 2 respectively, the metal flows. or is displaced so as to fill up the comers and create sharp edges.

In Figure 8, the dies I, 2, 4, 5, I, and 9 arev retracted so as to clear the corrugations of the ring for subsequent advance or feed of the strip. In Figure9 the swaging dies 3 and 6 are retracted leaving the strip entirely free for feed.

"As indicated in Figure 10, the strip is then fed forwardly against clamping die 4 for the next cycle of operation.

It will be noted that Figure 11 as far as the position of the dies is concerned, is a duplicate 'of Figure 2. However, the strip has been advanced through a number of cycles of operation the extreme end portion of the strip being shown in its ultimate form, that is with the walls of the corrugations bent for the purpose of closing or substantially closing the corrugations to form passageways. The pilot die 9 is for the purpose of piloting and guiding the stock, that is at each cycle it enters the adjacent corrugation of the strip and positions the strip properly.

When the machine is being operated at low speed, say strokes per minute, the strip delivered to the machine, and from which the rings are formed, is of low carbon steel containing approximately 0.40 per cent to 0.50 per cent car- 'bon, The preferred content of the steel utilized for low speed may be as follows:

Low carbon steel provides an excellent material for the rings since the operations of swaging the metal give the material the desirable charac- In Figure 3, dies 7 and Shave moved upwardly V teristics of hard steel. If steel cf'the foregoing content were run through the-machine at high speed, the result would be that fins would be formed at the sharp'corners of the corrugations. since the soft metal would be forced between the dies into the working clearances by the impact.

In order to prevent flow of metal into the clearances of the slides or dies when the machine is operating at high speed, and for the purpose of efflcientiy swaging thesharp cornersof the corrugation at high speed, a steel strip of higher carbon content is used. The steel for high speed production may have acontent within the fol- A lowing ranges: v

- Per cent Carbon 0.70 to0.75 Manganese 0.48 to 0.50 Phosphorus e 0.006 to 0.007 Sulphur 0.031 to 0.032 Silicon 0.130 to 0.135

By using a steel having 0.70 to 0.75 per cent carbon, the machine can be run at a speed of approximately 300 strokes per minute, without- 'of said bending die to form the other side wall of the corrugation and clamping the metal between another set of dies in alignment with the first set, thereafter retracting the bending die a slight amount and pressing the crown wall of the corrugation against said bending die by means of said die opposing said bending die, said opposing die having sharp corners whereby the corrugation is provided with sharp edges.

2. The method of forming a piston ring from a strip of metal comprising the steps of, forming a corrugation, supporting the side walls of the corrugation against displacement, engaging the crown wall of the corrugation between dies, one of which includes sharp corners for the purpose of swaging the crown wall, and forming a sharp crown thereon, retracting the other of said dies sufficiently to provide a swaging space, and thereafter moving said first die toward the retracted die and swaging the metal of the crown of the corrugation within the swaging space thus provided whereby the metal fills the sharp corners afforded between the supports for the side walls of the corrugation and the crown engaging surface of the lower die.

3. The method, of fabricating a piston ring from a strip of metal consisting of the steps of, clamping the metal between opposing dies, bending the metal by means of opposing dies to form corrugations, thereafter retracting one of the dies engaging the crown of the corrugation sumciently to provide a swaging space, and pressing the crown wall of the corrugation against said die within said space by means of the opposite die having sharp corners, whereby the corrugation is swaged to provide sharp edges.

VICTOR I ZAHODIAEIN'. 

